30 TEXT-BOOK OF PHYSIOLOGY 



of bioplasm found in nerves, which serves to transmit, with extreme rapidity, 

 molecular disturbances arising at the periphery to the brain, as well as from 

 the brain to the periphery. Muscle bioplasm also possesses the same power 

 in a high degree. 



Motility, or the power of executing apparently spontaneous movements, 

 is exhibited by many forms of cell bioplasm. In addition to the molecular 

 movements which take place in certain cells, other forms of movement are 

 exhibited, more or less constantly, by many cells in the animal body e.g., 

 the waving of cilia, the ameboid movements and migrations of white blood- 

 corpuscles, the activities of spermatozoa, the projection of pseudopodia, 

 etc. These movements, arising without any recognizable cause, are fre- 

 quently spoken of as spontaneous. Strictly speaking, however, all proto- 

 plasmic movement is the resultant of natural causes, the true nature of 

 which is beyond the reach of present methods of investigation. 



